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Glossary of WSA NonSurvey attributes (UKIDSSDR5)
This Glossary alphabetically lists all attributes used in the WSA NonSurvey database(s) held in the WSA. If you would like to have more information about the schema tables please use the Schema Browser (other Browser versions).

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

U

V

W

X

Y

Z

Z
Name	Schema Table	Database	Description	Type	Length	Unit	Default Value	Unified Content Descriptor
z11	[nspid]Multiframe	WSA NonSurvey	Spherical: Z11 {image primary HDU keyword: Z11}	real	4		-0.9999995e9
z7	[nspid]Multiframe	WSA NonSurvey	Coma: Z7 {image primary HDU keyword: Z7}	real	4		-0.9999995e9
z8	[nspid]Multiframe	WSA NonSurvey	Coma: Z8 {image primary HDU keyword: Z8}	real	4		-0.9999995e9
zAperMag3	[nspid]Source	WSA NonSurvey	Default point/extended source Z aperture corrected mag (2.0 arcsec aperture diameter) If in doubt use this flux estimator	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag3Err	[nspid]Source	WSA NonSurvey	Error in default point/extended source Z mag (2.0 arcsec aperture diameter)	real	4	mag	-0.9999995e9	ERROR
zAperMag4	[nspid]Source	WSA NonSurvey	Extended source Z aperture corrected mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag4Err	[nspid]Source	WSA NonSurvey	Error in extended source Z mag (2.8 arcsec aperture diameter)	real	4	mag	-0.9999995e9	ERROR
zAperMag6	[nspid]Source	WSA NonSurvey	Extended source Z aperture corrected mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	PHOT_MAG
zAperMag6Err	[nspid]Source	WSA NonSurvey	Error in extended source Z mag (5.7 arcsec aperture diameter)	real	4	mag	-0.9999995e9	ERROR
zaStrat	[nspid]VarFrameSetInfo	WSA NonSurvey	Strateva parameter a in Z band, see Sesar et al. 2007.	real	4		-0.9999995e9
			The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zbestAper	[nspid]Variability	WSA NonSurvey	Best aperture (1-6) for photometric statistics in the Z band	int	4		-9999
			Aperture magnitude (1-6) which gives the lowest RMS for the object. All apertures have the appropriate aperture correction. This can give better values in crowded regions than aperMag3 (see Irwin et al. 2007, MNRAS, 375, 1449)
zbStrat	[nspid]VarFrameSetInfo	WSA NonSurvey	Strateva parameter b in Z band, see Sesar et al. 2007.	real	4		-0.9999995e9
			The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zchiSq	[nspid]VarFrameSetInfo	WSA NonSurvey	Fit of Strateva function to data in Z band	real	4		-0.9999995e9
			The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zchiSqpd	[nspid]Variability	WSA NonSurvey	Chi square (per degree of freedom) fit to data (mean and expected rms)	real	4		0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zClass	[nspid]Source	WSA NonSurvey	discrete image classification flag in Z	smallint	2		-9999	CLASS_MISC
zClassStat	[nspid]Source	WSA NonSurvey	N(0,1) stellarness-of-profile statistic in Z	real	4		-0.9999995e9	STAT_PROP
zcStrat	[nspid]VarFrameSetInfo	WSA NonSurvey	Strateva parameter a in Z band, see Sesar et al. 2007.	real	4		-0.9999995e9
			The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zDeblend	[nspid]Source	WSA NonSurvey	placeholder flag indicating parent/child relation in Z	int	4		-99999999	CODE_MISC
			This CASU pipeline processing source extraction flag is a placeholder only, and is always set to zero in all passbands in the merged source lists. If you need to know when a particular image detection is a component of a deblend or not, test bit 4 of attribute ppErrBits (see corresponding glossary entry) which is set by WFAU's post-processing software based on testing the areal profiles aprof2-8 (these are set by CASU to -1 for deblended components, or positive values for non-deblended detections). We encode this in an information bit of ppErrBits for convenience when querying the merged source tables.
zEll	[nspid]Source	WSA NonSurvey	1-b/a, where a/b=semi-major/minor axes in Z	real	4		-0.9999995e9	PHYS_ELLIPTICITY
zeNum	[nspid]MergeLog	WSA NonSurvey	the extension number of this Z detector	tinyint	1			NUMBER
zErrBits	[nspid]Source	WSA NonSurvey	processing warning/error bitwise flags in Z	int	4		-99999999	CODE_MISC
zEta	[nspid]Source	WSA NonSurvey	Offset of Z detection from master position (+north/-south)	real	4	arcsec	-0.9999995e9	POS_EQ_DEC_OFF
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 2.0 (UKIDSS LAS and GPS; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.
zexpML	[nspid]VarFrameSetInfo	WSA NonSurvey	Expected magnitude limit of frameSet in this in Z band.	real	4		-0.9999995e9
			The expected magnitude limit of an intermediate stack, based on the total exposure time. expML=Filter.oneSecML+1.25*log10(totalExpTime). Since different intermediate stacks can have different exposure times, the totalExpTime is the minimum, as long as the number of stacks with this minimum make up 10% of the total. This is a more conservative treatment than just taking the mean or median total exposure time.
zExpRms	[nspid]Variability	WSA NonSurvey	Rms calculated from polynomial fit to minimum RMS as a function of magnitude in Z band	real	4	mag	-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zGausig	[nspid]Source	WSA NonSurvey	RMS of axes of ellipse fit in Z	real	4	pixels	-0.9999995e9	MORPH_PARAM
zHallMag	[nspid]Source	WSA NonSurvey	Total point source Z mag	real	4	mag	-0.9999995e9	PHOT_MAG
zHallMagErr	[nspid]Source	WSA NonSurvey	Error in total point source Z mag	real	4	mag	-0.9999995e9	ERROR
zIntRms	[nspid]Variability	WSA NonSurvey	Intrinsic rms in Z-band	real	4	mag	-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zMagMAD	[nspid]Variability	WSA NonSurvey	Median Absolute Deviation of Z magnitude	real	4	mag	-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zMagRms	[nspid]Variability	WSA NonSurvey	rms of Z magnitude	real	4	mag	-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zmaxCadence	[nspid]Variability	WSA NonSurvey	maximum gap between observations	real	4	days	-0.9999995e9
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zmeanMag	[nspid]Variability	WSA NonSurvey	Mean Z magnitude	real	4	mag	-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zmedCadence	[nspid]Variability	WSA NonSurvey	median gap between observations	real	4	days	-0.9999995e9
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zmedianMag	[nspid]Variability	WSA NonSurvey	Median Z magnitude	real	4	mag	-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zmfID	[nspid]MergeLog	WSA NonSurvey	the UID of the relevant Z multiframe	bigint	8			ID_FRAME
zminCadence	[nspid]Variability	WSA NonSurvey	minimum gap between observations	real	4	days	-0.9999995e9
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zmjExt	[nspid]Source	WSA NonSurvey	Extended source colour Z-J (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmjExtErr	[nspid]Source	WSA NonSurvey	Error on extended source colour Z-J	real	4	mag	-0.9999995e9	ERROR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmjPnt	[nspid]Source	WSA NonSurvey	Point source colour Z-J (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmjPntErr	[nspid]Source	WSA NonSurvey	Error on point source colour Z-J	real	4	mag	-0.9999995e9	ERROR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExt	[nspid]Source	WSA NonSurvey	Extended source colour Z-Y (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyExtErr	[nspid]Source	WSA NonSurvey	Error on extended source colour Z-Y	real	4	mag	-0.9999995e9	ERROR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPnt	[nspid]Source	WSA NonSurvey	Point source colour Z-Y (using aperMag3)	real	4	mag	-0.9999995e9	PHOT_COLOR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
zmyPntErr	[nspid]Source	WSA NonSurvey	Error on point source colour Z-Y	real	4	mag	-0.9999995e9	ERROR
			Default colours from pairs of adjacent passbands within a given set (e.g. Y-J, J-H and H-K for YJHK) are recorded in the merged source table for ease of querying and speedy querying via indexing of these attributes. Presently, the point-source colours and extended source colours are computed from the aperture corrected AperMag3 fixed 2 arcsec aperture diameter measures (for consistent measurement across all passbands) and generally good signal-to-noise. At some point in the future, this may be changed such that point-source colours will be computed from the PSF-fitted measures and extended source colours computed from the 2-d Sersic model profile fits.
znDof	[nspid]VarFrameSetInfo	WSA NonSurvey	Number of degrees of freedom of fit in Z band.	smallint	2		-9999
			The best fit solution to the expected RMS for all objects in the frameset. Objects were binned in ranges of magnitude and the median RMS (after clipping out variable objects using the median-absolute deviation) was calculated. The Strateva function $\zeta(m)>=a+b\,10^{0.4m}+c\,10^{0.8m}$ was fit, where $\zeta(m)$ is the expected RMS as a function of magnitude. The chi-squared and number of degrees of freedom are also calculated. This technique was used in Sesar et al. 2007, AJ, 134, 2236.
zndof	[nspid]Variability	WSA NonSurvey	Number of degrees of freedom for chisquare	int	4		-9999
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
znFlaggedObs	[nspid]Variability	WSA NonSurvey	Number of detections in Z band flagged as potentially spurious by u08a15Detection.ppErrBits	int	4		0
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
znGoodObs	[nspid]Variability	WSA NonSurvey	Number of good detections in Z band	int	4		0
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
znMissingObs	[nspid]Variability	WSA NonSurvey	Number of Z band frames that this object should have been detected on and was not	int	4		0
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zObjID	[nspid]Source	WSA NonSurvey	DEPRECATED (do not use)	bigint	8		-99999999	ID_NUMBER
			This attribute is included in source tables for historical reasons, but it's use is not recommended unless you really know what you are doing. In general, if you need to look up detection table attributes for a source in a given passband that are not in the source table, you should make an SQL join between source, mergelog and detection using the primary key attribute frameSetID and combination multiframeID, extNum, seqNum to associate related rows between the three tables. See the Q&A example SQL for more information.
zone	[nspid]ExternalSurveyTable	WSA NonSurvey	default (0) or special (n) zone	smallint	2			ID_REGION
zPA	[nspid]Source	WSA NonSurvey	ellipse fit celestial orientation in Z	real	4	Degrees	-0.9999995e9	POS_POS-ANG
zPetroMag	[nspid]Source	WSA NonSurvey	Extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	PHOT_MAG
zPetroMagErr	[nspid]Source	WSA NonSurvey	Error in extended source Z mag (Petrosian)	real	4	mag	-0.9999995e9	ERROR
zppErrBits	[nspid]Source	WSA NonSurvey	additional WFAU post-processing error bits in Z	int	4		0	CODE_MISC
zprobVar	[nspid]Variability	WSA NonSurvey	Probability of variable from chi-square (and other data)	real	4		0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zPsfMag	[nspid]Source	WSA NonSurvey	Point source profile-fitted Z mag	real	4	mag	-0.9999995e9	PHOT_MAG
zPsfMagErr	[nspid]Source	WSA NonSurvey	Error in point source profile-fitted Z mag	real	4	mag	-0.9999995e9	ERROR
zSeqNum	[nspid]Source	WSA NonSurvey	the running number of the Z detection	int	4		-99999999	ID_NUMBER
zSerMag2D	[nspid]Source	WSA NonSurvey	Extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	PHOT_MAG
zSerMag2DErr	[nspid]Source	WSA NonSurvey	Error in extended source Z mag (profile-fitted)	real	4	mag	-0.9999995e9	ERROR
zskewness	[nspid]Variability	WSA NonSurvey	Skewness in Z band (see Sesar et al. 2007)	real	4		-0.9999995e9
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
ztotalPeriod	[nspid]Variability	WSA NonSurvey	total period of observations (last obs-first obs)	real	4	days	-0.9999995e9
			The observations are classified as good, flagged or missing. Flagged observations are ones where the object has a ppErrBit flag. Missing observations are observations of the part of the sky that include the position of the object, but had no detection. All the statistics are calculated from good observations. The cadence parameters give the minimum, median and maximum time between observations, which is useful to know if the data could be used to find a particular type of variable.
zVarClass	[nspid]Variability	WSA NonSurvey	Classification of variability in this band	smallint	2		-9999
			The photometry is calculated for good observations in the best aperture. The mean, rms, median and median absolute deviation are quite standard. The skewness is calculated as in Sesar et al. 2007, AJ, 134, 2236. In each frameset, the mean and rms are used to derive a fit to the expected rms as a function of magnitude. The parameters for the fit are stored in VarFrameSetInfo and the value for the source is in expRms. This is subtracted from the rms in quadrature to get the intrinsic rms: the variability of the object beyond the noise in the system. The chi-squared is calculated, assuming a non-variable object which has the noise from the expected-rms and mean calculated as above. The probVar statistic assumes a chi-squared distribution with the correct number of degrees of freedom. The varClass statistic is 1, if the probVar>0.9 and intrinsicRMS/expectedRMS>3.
zXi	[nspid]Source	WSA NonSurvey	Offset of Z detection from master position (+east/-west)	real	4	arcsec	-0.9999995e9	POS_EQ_RA_OFF
			When associating individual passband detections into merged sources, a generous (in terms of the positional uncertainties) pairing radius of 2.0 (UKIDSS LAS and GPS; also non-survey programmes) or 1.0 (UKIDSS GPS, DXS and UDS) arcseconds is used, the higher value enabling pairing of moving sources when epoch separations may be several years. Such a large association criterion can of course lead to spurious pairings in the merged sources lists (although note that between passband pairs, handshake pairing is done: both passbands must agree that the candidate pair is their nearest neighbour for the pair to propagate through into the merged source table). In order to help filter spurious pairings out, and assuming that large positional offsets between the different passband detections are not expected (e.g. because of source motion, or larger than usual positional uncertainties) then the attributes Xi and Eta can be used to filter any pairings with suspiciously large offsets in one or more bands. For example, for a clean sample of QSOs from the LAS, you might wish to insist that the offsets in the selected sample are all below 1 arcsecond: simply add WHERE clauses into the SQL sample selection script to exclude all Xi and Eta values larger than the threshold you want.